ASSESSMENT OF THE IMPACT OF A COMPLEX OF TOXIC SUBSTANCES ON THE MORPHOLOGICAL STATE OF INTERNAL ORGANS IN A CHRONIC EXPERIMENT ON ANIMALS

Introduction. The study of the morphological state of the internal organs of Wistar rats exposed to prolonged dynamic stress from a complex of toxic substances (at a level of 1.5 MAC) under model conditions is of broad research interest, since it allows to evaluate the effects of these substances at the tissue and cellular level and identify pathological changes in relation to the control group, which was not exposed to this effect during the 180-day experiment. Aim of the research. Evaluation of the impact of a complex of toxic substances on the morphology of internal organs in a chronic experiment on animals. Materials and methods. When assessing the isolated impact of a complex of toxic substances (at a level of 1.5 MAC) on the morphological state of internal organs in a chronic experiment on laboratory Wistar rats, generally accepted and standardized methods were used. Animals (n = 60) of both sexes of sexual maturity age – 6 months (female rats weighing 198.1 ± 0.4 g (weight variation did not exceed 10%) and male rats weighing 325.2 ± 0.8 g (weight variation did not exceed 10%) were distributed in equal numbers (15 individuals in each) into experimental group 1 (chemical exposure – rats exposed in a 200 l inoculation chamber to a mixture of hydrocarbons: dimethylbenzene (a mixture of 2-, 3-, 4-isomers) – 225 mg/m3, gasoline solvent, fuel – 225 mg/m3, methylbenzene – 450 mg/m3, propan-2-one – 1200 mg/m3 at a concentration of 1.5 MAC for 0.5 hours, from 9.30 until 10 a.m., 5 days a week, and the control group 1 – rats, intact animals not exposed to the effects of these factors). After 180 days of exposure to chemical factors of the industrial environment, sexually mature animals – 12 months old (female rats weighing 381.7 ± 4.5 g (weight variation did not exceed 10%), and male rats weighing 245.0 ± 3.0 g (weight variation did not exceed 10%)) were euthanized with chloroform (3 ml of chloroform was injected into a desiccator with a syringe, and the time from the moment of administration to the onset of narcotic sleep was noted, the procedure was repeated with 5 and 10 ml of chloroform) and necropsy with the removal of internal organs for histopathological examination. The experiment was performed in accordance with the rules adopted by the European Convention for the Protection of Animals used for Experimental Scientific Purposes (Strasbourg, 1986), the Guidelines for the Care and Use of Laboratory Animals (Washington, 2011) after approval by the Ethics Committee of the Federal Budgetary Scientific Institution “Novosibirsk Research Institute of Hygiene” of Rospotrebnadzor. Results. Histomorphological analysis of the studied organs (myocardium, liver, lung, kidney, spleen) of Wistar rats revealed the presence of pathological changes in two or more studied organs of the experimental group during 180-day isolated exposure to a complex of chemical factors – organic solvents, compared with the control group, which may be a marker of the premature aging development. Conclusion. Isolated long-term periodic exposure to a complex of toxic substances (a mixture of aromatic hydrocarbons at a concentration of 1.5 MAC) contributed to the development of morphofunctional changes in two or more organs in rats of the experimental group on the 180th day of the experiment, compared to the control group (intact animals), which may be a marker of accelerated aging of the body’s biological systems.